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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.net;

import java.lang.annotation.Native;

/**
 * Interface of methods to get/set socket options.  This interface is
 * implemented by: <B>SocketImpl</B> and  <B>DatagramSocketImpl</B>.
 * Subclasses of these should override the methods
 * of this interface in order to support their own options.
 * <P>
 * The methods and constants which specify options in this interface are
 * for implementation only.  If you're not subclassing SocketImpl or
 * DatagramSocketImpl, <B>you won't use these directly.</B> There are
 * type-safe methods to get/set each of these options in Socket, ServerSocket,
 * DatagramSocket and MulticastSocket.
 * <P>
 *
 * @author David Brown
 */


public interface SocketOptions {

  /**
   * Enable/disable the option specified by <I>optID</I>.  If the option
   * is to be enabled, and it takes an option-specific "value",  this is
   * passed in <I>value</I>.  The actual type of value is option-specific,
   * and it is an error to pass something that isn't of the expected type:
   * <BR><PRE>
   * SocketImpl s;
   * ...
   * s.setOption(SO_LINGER, new Integer(10));
   * // OK - set SO_LINGER w/ timeout of 10 sec.
   * s.setOption(SO_LINGER, new Double(10));
   * // ERROR - expects java.lang.Integer
   * </PRE>
   * If the requested option is binary, it can be set using this method by
   * a java.lang.Boolean:
   * <BR><PRE>
   * s.setOption(TCP_NODELAY, new Boolean(true));
   * // OK - enables TCP_NODELAY, a binary option
   * </PRE>
   * <BR>
   * Any option can be disabled using this method with a Boolean(false):
   * <BR><PRE>
   * s.setOption(TCP_NODELAY, new Boolean(false));
   * // OK - disables TCP_NODELAY
   * s.setOption(SO_LINGER, new Boolean(false));
   * // OK - disables SO_LINGER
   * </PRE>
   * <BR>
   * For an option that has a notion of on and off, and requires
   * a non-boolean parameter, setting its value to anything other than
   * <I>Boolean(false)</I> implicitly enables it.
   * <BR>
   * Throws SocketException if the option is unrecognized,
   * the socket is closed, or some low-level error occurred
   * <BR>
   *
   * @param optID identifies the option
   * @param value the parameter of the socket option
   * @throws SocketException if the option is unrecognized, the socket is closed, or some low-level
   * error occurred
   * @see #getOption(int)
   */
  public void
  setOption(int optID, Object value) throws SocketException;

  /**
   * Fetch the value of an option.
   * Binary options will return java.lang.Boolean(true)
   * if enabled, java.lang.Boolean(false) if disabled, e.g.:
   * <BR><PRE>
   * SocketImpl s;
   * ...
   * Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
   * if (noDelay.booleanValue()) {
   * // true if TCP_NODELAY is enabled...
   * ...
   * }
   * </PRE>
   * <P>
   * For options that take a particular type as a parameter,
   * getOption(int) will return the parameter's value, else
   * it will return java.lang.Boolean(false):
   * <PRE>
   * Object o = s.getOption(SO_LINGER);
   * if (o instanceof Integer) {
   * System.out.print("Linger time is " + ((Integer)o).intValue());
   * } else {
   * // the true type of o is java.lang.Boolean(false);
   * }
   * </PRE>
   *
   * @param optID an {@code int} identifying the option to fetch
   * @return the value of the option
   * @throws SocketException if the socket is closed
   * @throws SocketException if <I>optID</I> is unknown along the protocol stack (including the
   * SocketImpl)
   * @see #setOption(int, java.lang.Object)
   */
  public Object getOption(int optID) throws SocketException;

  /**
   * The java-supported BSD-style options.
   */

  /**
   * Disable Nagle's algorithm for this connection.  Written data
   * to the network is not buffered pending acknowledgement of
   * previously written data.
   * <P>
   * Valid for TCP only: SocketImpl.
   *
   * @see Socket#setTcpNoDelay
   * @see Socket#getTcpNoDelay
   */

  @Native
  public final static int TCP_NODELAY = 0x0001;

  /**
   * Fetch the local address binding of a socket (this option cannot
   * be "set" only "gotten", since sockets are bound at creation time,
   * and so the locally bound address cannot be changed).  The default local
   * address of a socket is INADDR_ANY, meaning any local address on a
   * multi-homed host.  A multi-homed host can use this option to accept
   * connections to only one of its addresses (in the case of a
   * ServerSocket or DatagramSocket), or to specify its return address
   * to the peer (for a Socket or DatagramSocket).  The parameter of
   * this option is an InetAddress.
   * <P>
   * This option <B>must</B> be specified in the constructor.
   * <P>
   * Valid for: SocketImpl, DatagramSocketImpl
   *
   * @see Socket#getLocalAddress
   * @see DatagramSocket#getLocalAddress
   */

  @Native
  public final static int SO_BINDADDR = 0x000F;

  /**
   * Sets SO_REUSEADDR for a socket.  This is used only for MulticastSockets
   * in java, and it is set by default for MulticastSockets.
   * <P>
   * Valid for: DatagramSocketImpl
   */

  @Native
  public final static int SO_REUSEADDR = 0x04;

  /**
   * Sets SO_BROADCAST for a socket. This option enables and disables
   * the ability of the process to send broadcast messages. It is supported
   * for only datagram sockets and only on networks that support
   * the concept of a broadcast message (e.g. Ethernet, token ring, etc.),
   * and it is set by default for DatagramSockets.
   *
   * @since 1.4
   */

  @Native
  public final static int SO_BROADCAST = 0x0020;

  /**
   * Set which outgoing interface on which to send multicast packets.
   * Useful on hosts with multiple network interfaces, where applications
   * want to use other than the system default.  Takes/returns an InetAddress.
   * <P>
   * Valid for Multicast: DatagramSocketImpl
   *
   * @see MulticastSocket#setInterface(InetAddress)
   * @see MulticastSocket#getInterface()
   */

  @Native
  public final static int IP_MULTICAST_IF = 0x10;

  /**
   * Same as above. This option is introduced so that the behaviour
   * with IP_MULTICAST_IF will be kept the same as before, while
   * this new option can support setting outgoing interfaces with either
   * IPv4 and IPv6 addresses.
   *
   * NOTE: make sure there is no conflict with this
   *
   * @see MulticastSocket#setNetworkInterface(NetworkInterface)
   * @see MulticastSocket#getNetworkInterface()
   * @since 1.4
   */
  @Native
  public final static int IP_MULTICAST_IF2 = 0x1f;

  /**
   * This option enables or disables local loopback of multicast datagrams.
   * This option is enabled by default for Multicast Sockets.
   *
   * @since 1.4
   */

  @Native
  public final static int IP_MULTICAST_LOOP = 0x12;

  /**
   * This option sets the type-of-service or traffic class field
   * in the IP header for a TCP or UDP socket.
   *
   * @since 1.4
   */

  @Native
  public final static int IP_TOS = 0x3;

  /**
   * Specify a linger-on-close timeout.  This option disables/enables
   * immediate return from a <B>close()</B> of a TCP Socket.  Enabling
   * this option with a non-zero Integer <I>timeout</I> means that a
   * <B>close()</B> will block pending the transmission and acknowledgement
   * of all data written to the peer, at which point the socket is closed
   * <I>gracefully</I>.  Upon reaching the linger timeout, the socket is
   * closed <I>forcefully</I>, with a TCP RST. Enabling the option with a
   * timeout of zero does a forceful close immediately. If the specified
   * timeout value exceeds 65,535 it will be reduced to 65,535.
   * <P>
   * Valid only for TCP: SocketImpl
   *
   * @see Socket#setSoLinger
   * @see Socket#getSoLinger
   */
  @Native
  public final static int SO_LINGER = 0x0080;

  /**
   * Set a timeout on blocking Socket operations:
   * <PRE>
   * ServerSocket.accept();
   * SocketInputStream.read();
   * DatagramSocket.receive();
   * </PRE>
   *
   * <P> The option must be set prior to entering a blocking
   * operation to take effect.  If the timeout expires and the
   * operation would continue to block,
   * <B>java.io.InterruptedIOException</B> is raised.  The Socket is
   * not closed in this case.
   *
   * <P> Valid for all sockets: SocketImpl, DatagramSocketImpl
   *
   * @see Socket#setSoTimeout
   * @see ServerSocket#setSoTimeout
   * @see DatagramSocket#setSoTimeout
   */
  @Native
  public final static int SO_TIMEOUT = 0x1006;

  /**
   * Set a hint the size of the underlying buffers used by the
   * platform for outgoing network I/O. When used in set, this is a
   * suggestion to the kernel from the application about the size of
   * buffers to use for the data to be sent over the socket. When
   * used in get, this must return the size of the buffer actually
   * used by the platform when sending out data on this socket.
   *
   * Valid for all sockets: SocketImpl, DatagramSocketImpl
   *
   * @see Socket#setSendBufferSize
   * @see Socket#getSendBufferSize
   * @see DatagramSocket#setSendBufferSize
   * @see DatagramSocket#getSendBufferSize
   */
  @Native
  public final static int SO_SNDBUF = 0x1001;

  /**
   * Set a hint the size of the underlying buffers used by the
   * platform for incoming network I/O. When used in set, this is a
   * suggestion to the kernel from the application about the size of
   * buffers to use for the data to be received over the
   * socket. When used in get, this must return the size of the
   * buffer actually used by the platform when receiving in data on
   * this socket.
   *
   * Valid for all sockets: SocketImpl, DatagramSocketImpl
   *
   * @see Socket#setReceiveBufferSize
   * @see Socket#getReceiveBufferSize
   * @see DatagramSocket#setReceiveBufferSize
   * @see DatagramSocket#getReceiveBufferSize
   */
  @Native
  public final static int SO_RCVBUF = 0x1002;

  /**
   * When the keepalive option is set for a TCP socket and no data
   * has been exchanged across the socket in either direction for
   * 2 hours (NOTE: the actual value is implementation dependent),
   * TCP automatically sends a keepalive probe to the peer. This probe is a
   * TCP segment to which the peer must respond.
   * One of three responses is expected:
   * 1. The peer responds with the expected ACK. The application is not
   * notified (since everything is OK). TCP will send another probe
   * following another 2 hours of inactivity.
   * 2. The peer responds with an RST, which tells the local TCP that
   * the peer host has crashed and rebooted. The socket is closed.
   * 3. There is no response from the peer. The socket is closed.
   *
   * The purpose of this option is to detect if the peer host crashes.
   *
   * Valid only for TCP socket: SocketImpl
   *
   * @see Socket#setKeepAlive
   * @see Socket#getKeepAlive
   */
  @Native
  public final static int SO_KEEPALIVE = 0x0008;

  /**
   * When the OOBINLINE option is set, any TCP urgent data received on
   * the socket will be received through the socket input stream.
   * When the option is disabled (which is the default) urgent data
   * is silently discarded.
   *
   * @see Socket#setOOBInline
   * @see Socket#getOOBInline
   */
  @Native
  public final static int SO_OOBINLINE = 0x1003;
}
